Cartridge-actuated fastener-driving tools

ABSTRACT

A cartridge-actuated tool adapted to explosively drive fasteners is provided which ejects the actuating cartridge into a propulsion chamber while controlling cartridge rupture so as to avoid tool damage.

0 United States Patent 1191 [111 3,709,421 Kolmar 1 Jan. 9, 1973 [54]CARTRIDGE-ACTUATED FASTENER- [56] References Cited DRIVING TOOLS UNITEDSTATES PATENTS [75] Inventor: Herbert Kolmar, Burgoberbach near 165,Germany 2,893,279 7/1959 Haskell etal ..227/10 x 3,045,242 7/1962 Adolph..227/10 [73] Assignee: lmpex-Essen Vertrieb Von Werkzeu- 3,115,63612/1963 Elliott ..1..227/10 gen GmbH, Ansbach, Germany 3,285,131 11/1966Lewis ....227/9 X 3,353,445 11/1967 Temple et a1. ..227/10 X [22] Filed:May 17, 1971 [21] A N 143,823 Primary Examiner-Granville Y. Cluster, Jr.

Attorney-Pendleton, Neuman, Williams & Anderson [30] Foreign ApplicationPriority Data [57] ABSTRACT May 30, 1970 Germany ..P 20 26 570.7 Acartridge actuated tool adapted to explosively drive fasteners isprovided which ejects the actuating car- [52] U.S. Cl ..227/10 tridgeinto a propulsion chamber while controlling [51] Int. Cl ..B25c 1/14cartridge rupture so as to avoid too-l damage [58] Field of Search..227/9, 10, ll

3 Claims, 2 Drawing Figures PAIENTEDJAN 9 ma 3.709421 lnvento r A TTORNEW/J CARTRIDGE-ACTUATED FASTENER-DRIVING TOOLS This invention relatesto cartridge-actuated fastenerdriving tools for explosively insertingbolts, pins, studs or other like fasteners.

The invention is concerned with cartridge-actuated fastener-drivingtools comprising a thrust plunger displaceable by the combustion gasesfrom a detonated cartridge, the thrust plunger having its rearward endarranged to be received in a propulsion chamber, and a cartridge chamberbeing provided to issue into the propulsion chamber and to receive acartridge in such manner that the base of the cartridge faces towardsthe propulsion chamber, whereby the cartridge case is ejected into thepropulsion chamber after detonation by the pressure generated by thecombustion gases.

Known cartridge-actuated fastener-driving tools of the above-mentionedtype in which the cartridge chamber is located either in the rearwardend of the thrust plunger or alternatively in a barrel having a portionencircling the thrust plunger are characterized in that the cartridgecase is designed to be withdrawn or ejected automatically from thecartridge chamber upon the forward movement of the thrust plunger underthe pressure of the burning gases, and thus no special mechanicalwithdrawal elements are necessary. However, in these known tools thereis a danger of disintegration or splitting of the cartridge casefrequently occurring due to the considerable difference in gas pressurebetween the interior and exterior of the cartridge case, with the resultthat functional damage to the tool may arise and the operation of thetool may in consequence be considerably impaired. In order to meet thisproblem attempts have already been made to reduce the pressuredifference between the interior and exterior of the cartridge case byproviding channels for the gases in the rearward end of the thrustplunger which defines the cartridge chamber, these channels extendingrearwardly towards the propulsion chamber and at an angle to the base ofthe cartridge chamber.

However, even with this modification, splitting of the cartridge case isnot avoided. Moreover, due to the provision of the special channels forthe gases the car tridge chamber itself is weakened. In addition, it isknown in firearms to provide small longitudinal grooves either in thecartridge case or in the cartridge chamber for the purpose of equalizingthe gas pressure and thus reducing the bursting pressure in thecartridge case. The combustion gases from the cartridge case can escapealong these small longitudinal grooves and can pass rearwards betweenthe case and the cartridge chamber wall so that in this way the pressureon the walls is reduced and the cartridge case can be withdrawn moreeasily. However, the above-mentioned measures are not satisfactory forcartridge-actuated fastener-driving tools which include a thrustplunger.

It is an object of the present invention to provide a cartridge-actuatedfastener-driving tool having a. thrust plunger and which is operative insuch a way that ejection of the spent cartridge case occursautomatically by the action of the gas pressure, and more particularlyso that the cartridge case is ejected without being split or broken up.

This is achieved in accordance with the present invention by theprovision of a cartridge-actuated fastener-driving tool comprising athrust plunger displaceable by the combustion gases from a detonatedcartridge, the thrust plunger having its rearward end arranged to bereceived in a propulsion chamber, a cartridge chamber issuing into thepropulsion chamber and arranged to receive a cartridge in such mannerthat the base of the cartridge faces towards the propulsion chamber,whereby the cartridge case is ejected into the propulsion chamber by gaspressure after detonation, characterized in that desired rupture areasfor the cartridge case are provided in the wall of the cartridge chamberadjacent to the propulsion chamber in the form of axially extendingrecesses.

In this way the cartridge case breaks open without splitting afterdetonation of the charge at predetermined areas which are positioned asfar as possible close to the base of the cartridge :50 that the highinternal pressure generated in the cartridge case by the detonation canbe vented swiftly out into the propulsion chamber and with the resultthat the cartridge case is ejected without splitting and withoutimpairment of the driving force generated by the combustion gases.

The invention is particularly appropriate for use withcartridge-actuated fastener-driving tools which are provided with abarrel fitted with a firing pin and having a portion encircling therearward end of the thrust plunger to define the propulsion chamber,with the cartridge chamber provided in the rear end of the thrustplunger. In such a case, and in accordance with a preferred feature ofthe invention, the desired rupture areas are defined by slots providedin the rearward section of the cartridge chamber wall in the form ofinclined slots which increase in cross-sectional area towards thepropulsion chamber and which are substantially trapezoidal incross-section with one side wall of each slot meeting the cartridgechamber wall at a sharp angle and with the other side wall of each slotmeeting the cartridge chamber wall in a smooth curve. By this means,breaking open of the cartridge case at the predetermined rupture areasin the cartridge chamber is favored and the danger of splitting of thecartridge case with its undesirable attendant effects is avoided inpractice.

In order that the invention may be more fully understood a preferredembodiment in accordance with the invention will now be described by wayof example and with reference to the accompanying drawing, in which:

FIG. 1 is a view, partly in section, of those parts of acartridge-actuated fastener-driving tool incorporatinga thrust plungerwhich are essential to the present invention; and,

FIG. 2 is a cross-section taken along the line lI-II of FIG. 1.

It should be realized that only those parts of the fastener-driving toolwhich are relevant to the present invention are illustrated in thedrawing and are described hereinafter. The fastener-driving too]comprises a barrel 1 which defines a propulsion chamber 1' formed as arecess in the forward end of thebarrel l. A thrust plunger 2 isdisplaceably held in the propulsion chamber 1', and in the ready-to-fireposition shown in the drawing the rear end of the thrust plunger fitsfully into the propulsion chamber 1'. A cartridge chamber 5 in the formof a multiple stepped bore is provided in the rear end of the thrustplunger 2 and receives a cartridge 3 which has its base rim 3 facingtowards the propulsion chamber 1' and projecting into a correspondinglyshaped recess 1" in the barrel wall forming the base of the propulsionchamber. A firing pin 4 is mounted in the barrel for axial movementrelative thereto so as to cause detonation of the cartridge.

Inclined slots 2', three in number in this preferred embodiment, areprovided in the wall of the rear section of the cartridge chamber. Theseslots 2 increase in cross-sectional area towards the propulsion chamber1 and, as shown in FIG. 2, are each of substantially trapezoidalcross-section. One side wall 2" of each slot 2 meets the cartridgechamber wall at a sharp angle, while on the other hand the other sidewall 2" of each slot meets the cartridge chamber Wall in a smooth curve.These slots 2 define desired rupture areas of the cartridge case which,under the influence of the internal pressure generated by thedetonation, bursts open in the manner shown in FIG. 2, i.e., along thelines defined by the junction of the slot side walls 2" with thecartridge chamber wall. This results in a swift pressure equalizationbetween the interior of the cartridge case and the exterior of thecartridge case so that further splitting or even disintegration of thecartridge case is reliably prevented.

lclaim:

1. A cartridge-actuated fastener-driving tool comprising a barrel fittedwith a firing pin and having a propulsion chamber disposed therein; athrust plunger having a rear portion disposed in said chamber; saidthrust plunger having a cartridge chamber at least partially disposed insaid rear portion; the cartridge chamber being adapted to receive acartridge in such manner that the base of the cartridge faces thepropulsion chamber whereby the cartridge case is ejected into thepropulsion chamber by gas pressure after cartridge detonation; the wallportion of the cartridge chamber disposed adjacent to the propulsionchamber having axially extending rupture recesses for a cartridgedisposed in the cartridge chamber.

2. The tool of claim 1 in which said rupture recesses increase incross-sectional area in the direction of the propulsion chamber.

3. The tool of claim 1 in which said rupture recesses are substantiallytrapezoidal in cross-section with one side wall of each recess meetingthe cartridge chamber wall at a sharp angle, and with the other sidewall of each recess meeting the cartridge chamber wall in a smoothcurve.

1. A cartridge-actuated fastener-driving tool comprising a barrel fittedwith a firing pin and having a propulsion chamber disposed therein; athrust plunger having a rear portion disposed in said chamber; saidthrust plunger having a cartridge chamber at least partially disposed insaid rear portion; the cartridge chamber being adapted to receive acartridge in such manner that the base of the cartridge faces thepropulsion chamber whereby the cartridge case is ejected into thepropulsion chamber by gas pressure after cartridge detonation; the wallportion of the cartridge chamber disposed adjacent to the propulsionchamber having axially extending rupture recesses for a cartridgedisposed in the cartridge chamber.
 2. The tool of claim 1 in which saidrupture recesses increase in cross-sectional area in the direction ofthe propulsion chamber.
 3. The tool of claim 1 in which said rupturerecesses are substantially trapezoidal in cross-section with one sidewall of each recess meeting the cartridge chamber wall at a sharp angle,and with the other side wall of each recess meeting the cartridgechamber wall in a smooth curve.